The present disclosure relates to fluid filtration, particularly filters employed in line for filtering pressurized fluid such as encountered in petro chemical refining, chemical processing, hydraulic fluid systems and filtration of water and aqueous solutions. In such filtration applications, barrier filters comprised of wire mesh, fabric or screens, and combinations thereof, have been employed in a pressure vessel disposed in-line in a fluid system. Typically, the pressure vessel has a removable lid openable for permitting removal and replacement of a filter cartridge.
In service, the filter media or barrier causes filtered particles of contamination to accumulate on the inlet or pressure side of the filter and causes an increase in differential pressure across the filter media which, in turn, creates a reduction in the process flow.
Heretofore, backwashing by reverse flow has been employed as a means of dislodging filtered particles and contaminates from the surface of the filter media and discharging same to a drain. This often requires shutting down process flow and applying reverse flow pressure to effect the backwashing and also may result in a high volume of contaminated process liquid to be disposed of with the trapped material removed from the filter.
In some filtration systems employing a cylindrical configuration for the barrier or filter media, a rotating member has been heretofore employed with a drain port disposed closely adjacent the inlet pressure side of the filter media and rotated thereabout with the port being open to a drain at substantially atmospheric pressure. This has provided a reverse pressure differential between the discharge pressure side of the filter media and the drain port thus providing localized back flushing or backwashing as the ported member is rotated about the cylindrical filter media. This technique is applicable to cylindrical filter media having a generally smooth interior inlet pressure side; however, where the filter media is formed in a cylindrical pleated configuration, the discharge port of the rotating member is ineffective to create a substantial pressure differential in the pleated regions and thus the backwashing is less effective for such filter configurations.
Accordingly, it has been desired to provide a way or means for removing trapped particles and contaminants from a pleated cylindrical fluid filter in service without the need to shut down the system and apply backwashing pressure to the outlet or the need for removing the filter media cartridge from the pressure vessel.